Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have the problem that a server is rejecting emails from my mail server if they are replies to previous mails. If a new mail is sent it can be delivered.

Either I receive this error message

host[x.x.x.x] said: 554 5.7.1 Command rejected
    (in reply to end of DATA command)

or I do not get any message but only an empty message is delivered to the receiver.

I've tested my server with for blacklist entries or SMTP errors but everythink looks fine. The receiving server also has no SMTP errors, except it doesn't accept SSL/TLS connections.

The mails are sent/replied with Outlook 12. My mail server runs postfix and dovecot.

share|improve this question
Are there any more logs that correspond to the message? There's something odd going on in the commands that Outlook is sending, it could be something you could change in the postfix configuration, but first you need to understand what the wrong command is.. – NickW Feb 14 '13 at 12:19
Can I get more info/log the traffic for the problematic domain only? I do not have Outlook installed myself, so I have to ask someone to reply again and cannot use wireshark. – Dehalion Feb 14 '13 at 12:54

You may use tcpdump (-X) / wireshark to have a look at what Outlook is doing (not the packet metadata but the packet contents).

share|improve this answer
Can I use tcpdump on the server and restrict it to only smtp-traffic to a specific mail server? – Dehalion Feb 14 '13 at 12:55
You can tell tcpdump which packets to show. You can restrict that to the ip (or network) address of the client (why "server"?). – Hauke Laging Feb 14 '13 at 12:59
Ok, "server" was the wrong term. Restricting to one ip should be enough, I hope they don't have more than one mail servers for that domain running :D – Dehalion Feb 14 '13 at 13:36

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.